title: Membrane-bound oxygen reductases of the anaerobic sulfate-reducing Desulfovibrio vulgaris Hildenborough: roles in oxygen defence and electron link with periplasmic hydrogen oxidation.
abstract: Cytoplasmic membranes of the strictly anaerobic sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough contain two terminal oxygen reductases, a bd quinol oxidase and a cc(b/o)o3 cytochrome oxidase (Cox). Viability assays pointed out that single Δbd, Δcox and double ΔbdΔcox deletion mutant strains were more sensitive to oxygen exposure than the WT strain, showing the involvement of these oxygen reductases in the detoxification of oxygen. The Δcox strain was slightly more sensitive than the Δbd strain, pointing to the importance of the cc(b/o)o3 cytochrome oxidase in oxygen protection. Decreased O2 reduction rates were measured in mutant cells and membranes using lactate, NADH, ubiquinol and menadiol as substrates. The affinity for oxygen measured with the bd quinol oxidase (Km, 300 nM) was higher than that of the cc(b/o)o3 cytochrome oxidase (Km, 620 nM). The total membrane activity of the bd quinol oxidase was higher than that of the cytochrome oxidase activity in line with the higher expression of the bd oxidase genes. In addition, analysis of the ΔbdΔcox mutant strain indicated the presence of at least one O2-scavenging membrane-bound system able to reduce O2 with menaquinol as electron donor with an O2 affinity that was two orders of magnitude lower than that of the bd quinol oxidase. The lower O2 reductase activity in mutant cells with hydrogen as electron donor and the use of specific inhibitors indicated an electron transfer link between periplasmic H2 oxidation and membrane-bound oxygen reduction via the menaquinol pool. This linkage is crucial in defence of the strictly anaerobic bacterium Desulfovibrio against oxygen stress.
authors.affiliation: Laboratoire de Chimie Bactérienne, CNRS-UMR7283, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
authors.forename: F
authors.initials: F
authors.lastname: Ramel
authors.affiliation: Laboratoire de Chimie Bactérienne, CNRS-UMR7283, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
authors.forename: A
authors.initials: A
authors.lastname: Amrani
authors.affiliation: Laboratoire de Chimie Bactérienne, CNRS-UMR7283, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
authors.forename: L
authors.initials: L
authors.lastname: Pieulle
authors.affiliation: Laboratoire de Chimie Bactérienne, CNRS-UMR7283, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
authors.forename: O
authors.initials: O
authors.lastname: Lamrabet
authors.affiliation: Petroleum Microbiology Research Group, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary T2N 1N4, AB, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Voordouw
authors.affiliation: Laboratoire de Métabolisme Énergétique Cellulaire, IBGC-CNRS, et Université Bordeaux Segalen, 1 Rue Camille Saint-Saëns, 33077 Bordeaux CEDEX, France.
authors.forename: N
authors.initials: N
authors.lastname: Seddiki
authors.affiliation: Laboratoire de Métabolisme Énergétique Cellulaire, IBGC-CNRS, et Université Bordeaux Segalen, 1 Rue Camille Saint-Saëns, 33077 Bordeaux CEDEX, France.
authors.forename: D
authors.initials: D
authors.lastname: Brèthes
authors.affiliation: Laboratoire de Chimie Bactérienne, CNRS-UMR7283, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
authors.forename: M
authors.initials: M
authors.lastname: Company
authors.affiliation: Laboratoire de Chimie Bactérienne, CNRS-UMR7283, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
authors.forename: A
authors.initials: A
authors.lastname: Dolla
authors.affiliation: Laboratoire de Chimie Bactérienne, CNRS-UMR7283, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20, France.
authors.forename: G
authors.initials: G
authors.lastname: Brasseur
mesh_terms: D000693:Anaerobiosis; D016969:Desulfovibrio vulgaris / Q000201:enzymology / Q000378:metabolism*; D004579:Electron Transport; D017353:Gene Deletion; D006859:Hydrogen / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D050296:Microbial Viability; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D019897:Periplasm / Q000201:enzymology / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*
chemical_list: D008565:Membrane Proteins; D013431:Sulfates; D006859:Hydrogen; D010088:Oxidoreductases; D010100:Oxygen